Oil bath lubrication for mechanism



May 23, 1967 J. s. VAUGHN OIL: BATH LUBRICATION FOR MECHANISM FiledMarch 24, 1964 INVENTOR. JACK 5. VAUGHN United States Patent 3,321,043OIL BATH LUBRICATION FOR MECHANISM Jack S. Vaughn, Sayre, Pa., assignorto IngersolLRand Company, New York, N.Y., a corporation of New JerseyFiled Mar. 24, 1964, Ser. No. 354,241 Claims. (Cl. 184-1) This inventionrelates to mechanism lubrication and more particularly to oil bathlubrication for impact mecha- IllSIIlS.

Heretofore, in impact mechanisms utilizing lubricant bath lubrication,it was necessary to seal the motor means from the impact mechanism toprevent the lubricant from leaking into the motor means. Also the impactmechanism must be sealed at the anvil so the lubricant will not leak tothe outside of the impact tool. The seal on the motor end has to be runat motor speed, which is very high. Under no load conditions the anvilwill run approximately this same speed. Both seals are thereforevulnerable to overheating resulting in frequent failure of the seals.

It is the general object of the present invention to avoid and overcomethe foregoing and other difficulties of and objections to prior artpractices by the provision of an impact mechanism that will greatlyreduce seal failure.

Another object of the present invention is to reduce the number of sealsfor an impact mechanism.

The aforesaid objects of the present invention, and other objects whichwill become apparent as the description proceeds, are achieved byproviding an impact mechanism of the class wherein a hammer strikes ananvil to impart rotation to said anvil. The combination with the impactmechanism of reservoir means encasing the hammer mechanism to holdlubricating fluid. In addition the provision of seal means disposed onsaid anvil between the reservoir means and the anvil and rotating withthe anvil to seal the lubricating fluid in the reservoir means.

For a better understanding of the present invention reference should behad to the accomanying drawings, wherein like numerals of referenceindicate similar parts throughout the several views and wherein:

FIG. 1 is a longitudinal sectional view illustrating an impactmechanism;

FIG. 2 is a vertical sectional view taken along the line 2-2 of FIG. 1in the direction of the arrows and illustrating the engaging anddisengaging members of the impact mechanisms;

FIG. 3 is an enlarged sectional view of the seal shown in FIG. 1.

Although the principles of the present invention are broadly applicableto high speed mechanisms, the present invention is particularly adaptedfor use in conjunction with impact mechanisms and hence it has been soillustrated and will be so described.

With specific reference to the form of the present invention illustratedin the drawings, and referring particularly to FIG. 1, an impact wrenchis indicated generally by the reference numeral 10. The impact wrench isof the standard type well known in the art having an anvil 12, disposedin a casing 13. The anvil 12 is provided at its working end 14- with asocket 16 capable of receiving a nut (not shown) which nut is to bedriven into a work piece (not shown). A hammer frame 20 containing ahammer 18 is disposed around the anvil 12 in the casing 13. The hammer18 oscillates about a hammer pin 22 to strike a dog 24 on the anvil 12and thereby rotate the anvil 12. The hammer 18 is controllably rotatedthrough a drive means, such as a rotor shaft 26 and cam 28 as shown inFIG. 1. It is understood that the rotor shaft is rotatably driven by anynumber of well known motor means such as an air motor (not shown) or anelectric motor (not shown).

It will be understood by those skilled in the art that the hammer 18 cancause the anvil 12 to rotate at approximately the same speed as themotor under no load conditions. The anvil speed under load is the B.P.M.rate which is considerably less than the motor speed.

In order to provide constant and effective lubrication to the anvil 12and hammer 18, fluid bath lubrication is utilized. Reservoir means, suchas a can 36', is disposed in the casing 13, encasing the anvil 12, thehammer 18, the hammer frame 20 and the hammer pin 22, as shown inFIG. 1. As is apparent from the drawings, the pin 22 is fixed to the can30 so that when the hammer l8 and hammer frame .20 rotate, the reservoiror can 30 also rotates at the same speed. When no load or a load below apredetermined minimum is applied to the anvil through the socket 16, thehammer 18, through the dog 24, will cause the anvil 12 to continuouslyrotate with the hammer and reservoir 30. When a load above thepredetermined minimum is applied to the anvil as when the fastener to betightened reaches a certain torque, the anvil stops rotating and thehammer swings away from the dog 24. When the hammer 18 is clear, thehammer makes one revolution relative to the anvil 12. As the hammerrevolves about the anvil, the dog 24 swings the hammer back into aposition to deliver an impact to the dog 24 and rotate the anvil 12 acertain amount. Thus, above the predetermined torque, the rotation ofthe anvil with the hammer and reservoir 36) becomes intermittent. Thecan 30 is supplied by a lubricating fluid, such as oil, through ports 32and 34 disposed on the can 30 and the casing 13 respectively. In orderto prevent the lubricating fluid from leaking out of the can 30, sealmeans such as a dynamic seal 36 and a static seal 38 are provided.

The dynamic seal 36 is disposed between the can 30 and the anvil 1.2 andis attached to the circumference of the anvil 12 in order to rotate withthe anvil 12.

The dynamic seal 36 comprises three friction seals 35a, 35b and 360 asshown in FIGS. 1 and 3. Two of the seals 36a and 36c fit in the can 30(note the O ring touching the can 30 at X). The third seal 36b fits onthe anvil 12 (note the O-ring touching the can 30 at Y). In addition theseals 36a, 36b and 36c function as face seals and are in contact atpoint Z as shown in FIG. 1. The faces of the seals Sea, 36!) and sec arekept in contact by the urging action of a load spring 37 as shown inFIG. 3. The two O-rings X engage the can 3G to prevent fluid fromleaking around the can and prevent rotation of the can 30 relative tothe rings 36a and 360. The O-ring Y engages the anvil 12 to preventleakage around the anvil and prevent rotation between the anvil and thering 3612. Therefore, as the reservoir 30 rotates relative to the avil12, the rings 36a and 36c rotate relative to the ring 36!). The seal islubricated by the capillary action of fluid in the can reaching the sealas and between rings 36a, b and c.

It will now be understood that under no load conditions the anvil 12will rotate at approximately the same speed as the motor and the impactmechanism will not function thus maintaining the seals 36a, 36b and 36cstatic because there is no relative rotation between the can 30 and theanvil 12. This is a real advantage because the seals 36a, 3fib and 36ccan not be heated up under free speed no load conditions. Under loadconditions the impact mechanism will impact thus effecting the seals36a, 36b and 36c. However under load conditions the speed of the seals36a, 36b ad 36c is greatly reduced because the seal speed isapproximately the B.P.M. of the impact wrench which is much less thanthe impact speed.

It can thus be seen that the dynamic seal life is pre- 61 served throughthe reduction and lack of relative motion between the anvil 12 and thecan 30 at critical high speed operation and the further reduction ofrelative motion between anvil 12 and the can 30 at impact conditions. Itwill also be see that the anvil side 40 of the dynamic seal 36 will bedry and that the can side 42 will be coated with the lubricant in thecan 30. This further serves to prolong the life of the dynamic seal 36,because the can side 42 of the dynamic seal 36, which is the frictionside,

ill be subjected to the friction of rotation and since the can side 42will be adequately lubricated the dynamic seal 36 will have a longerlife.

The static seal 38 can be any type of well known seal, such as anO-ring, and is disposed in a recess 44 in the cam 28, and serves toprevent lubricating fluid from escaping from the can 30, to the motorarea of the impact wrench 10.

It will be recognized by those skilled in the art that the objects ofthe present invention have been achieved by providing an impactmechanism that will greatly reduce seal failure and also an impactmechanism that contains only two seals.

While in accordance with the patent statutes a preferred embodiment ofthe present invention has been illustrated and described in detail, itis to be particularly understood that the invention is not limitedthereto or thereby.

I claim:

1. An impact mechanism comprising:

a reservoir containing lubricating fluid;

a hammer mounted within said reservoir;

means for rotating said hammer and reservoir;

an anvil extending into said reservoir and surrounded by said hammer forcontinuous rotation with said hammer and reservoir when a load below apredetermined minimum is applied to said anvil and for intermittentrotation with said hammer and reservoir when a load above said minimumis applied to said anvil whereby said lubricating fluid lubricates thecontacting surfaces between said anvil and said hammer; and

first seal means between said reservoir and said anvil for.preventingloss of lubricating fluid from said reservoir.

2. The impact mechanism of claim 1 wherein said first seal meansincludes a plurality of friction rings in contact with each other andencircling said anvil, at least one of said friction rings having anO-ring engaging said reservoir and at least one of said friction ringshaving a O-ring engaging said anvil.

3. The impact mechanism of claim 2 wherein said first seal includesmeans for biasing said friction rings together.

4. The impact mechanism of claim 3 further including second seal meansbetween said hammer and said rotating means.

5. The apparatus of claim 4 further including a casing surrounding saiddrive means, reservoir, hammer and anvil.

References Cited by the Examiner UNITED STATES PATENTS 2,501,542 3/1950Sheldon 173 123 X 3,070,378 12/1962 Bojako et a1. 277- s3 X 3,123,3653/1964 Gorman 277 s3 3,169,775 2/1965 Macaluso 277-433 X 3,210,96310/1965 Burnett 173 93 X LAVERNE D. GEIGER, Primary Examiner. E. J.EARLS, Assistant Examiner.

1. AN IMPACT MECHANISM COMPRISING: A RESERVOIR CONTAINING LUBRICATINGFLUID; A HAMMER MOUNTED WITHIN SAID RESERVOIR; MEANS FOR ROTATING SAIDHAMMER AND RESERVOIR; AN ANVIL EXTENDING INTO SAID RESERVOIR ANDSURROUNDED BY SAID HAMMER FOR CONTINUOUS ROTATION WITH SAID HAMMER ANDRESERVOIR WHEN A LOAD BELOW A PREDETERMINED MINIMUM IS APPLIED TO SAIDANVIL AND FOR INTERMITTENT ROTATION WITH SAID HAMMER AND RESERVOIR WHENA LOAD ABOVE SAID MINIMUM IS APPLIED TO SAID ANVIL WHEREBY SAIDLUBRICATING FLUID LUBRICATES THE CONTACTING SURFACES BETWEEN SAID ANVILAND SAID HAMMER; AND FIRST SEAL MEANS BETWEEN SAID RESERVOIR AND SAIDANVIL FOR PREVENTING LOSS OF LUBRICATING FLUID FROM SAID RESERVOIR.